Prior arts relating to electronic book display control methods for changing display scenes just like turning pages of a printed book are disclosed in Japanese Laid-Open Patent Publication No. 64-86191 and 2-181864. The former provides an electronic book device that has a control portion including a memory for storing two kinds of images, two selectors and a speed controller and can changeover a display image just as it turns a page of the book by presenting a next image on a part of a display area of a preceding image and by gradually increasing the next image and finally displaying a full image on a full screen. The latter provides a user-friendly electronic book device that has a book-contour display portion to display a contour image of the book and open the book when the user points a position on a fore-edge of the book and giving the user a feeling of reading the book by changing the thickness of the fore-edge of the book displayed on the display portion.
Japanese Laid-Open Patent Publication No. 5-53726 describes a display tablet device that detects a trace, a direction and a speed of movement of a pen on a display screen by an input detector.
With a display device for displaying a plurality of data-recorded sheets such as data of plural document pages and image data of a image filing device, one may often change in succession display images to search objective data. In this instance, if display data is fully displayed every time, high-speed changeover of data images cannot be realized and the retrieving efficiency is decreased. In view of the above, an image filing device disclosed in Japanese Laid-Open Patent Publication No. 1-269174 performs the retrieval of objective data in a data image memory in such a manner that a part area of data being displayed on the screen is designated first by the user, the data is then retrieved from the specified data area in the image data memory and displayed by repeating the above cycle of retrieval operations to find the objective data. Japanese Laid-Open Patent Publication No. 4-120670 also discloses such a method that original image data and contracted data of the original image are stored in a memory device, contracted data is read in retrievaling and displayed in succession like turning pages at a high speed.
However, methods disclosed in Japanese Laid-Open Patent Publications No.64-86191 and No. 2-181864 have such drawbacks that the display is controlled according to the data calculated by the speed controller and hence it is difficult to flexibly change the speed of display in accordance with the type and contents of data stored in a memory. For example, it is impossible to change a display image just as turning of a page of the book in spread state. The both systems have the limit to its display control and cannot realize, in this sense, a display that is so called friendly to users.
The above systems can turn pages at a specified display speed calculated by its controller and hence cannot control the display speed in accordance with the contents of data to be displayed or skip a page.
The system disclosed in Japanese Laid-Open Patent Publication No. 5-53726 involves such a problem that it requires, besides display memory, the provision of an additional image-memory whose capacity is two times larger than the display area.
The system disclosed in Japanese Laid-Open Patent Publication No. 1-269174 has no consideration of a method for storing display data necessary for changing page images at a high speed and hence requires time for turning pages.
The system disclosed in Japanese Laid-Open Patent Publication No. 4-120670 has to store a large number of data because the contracted images preliminarily registered include redundant data.
Furthermore, the above systems cannot be adapted to turning pages of a recent available document whose pages may include various kinds of data such as characters, pictures, audio signals and moving pictures on one page.
To solve the above problems involved in the prior arts, the present invention is intended to provide a display changeover control portion including a table for storing column information necessary for turning pages and means for selecting addresses of a display preparation image data storage portion and image data of a current display page and a next display page from the column information, which can control the display speed flexibly in accordance with image data to be displayed, realizing changeover of display images just as turning pages of a printed book.
To solve the problem involved in the prior arts, the present invention also aims at saving of an image data memory capacity to a half the memory capacity of the prior art devices by providing a data latch for reading image data from the display image data storage portion and temporally storing it.
Another object of the present invention is to realize high-speed turning of pages by storing information of a display image sequence in a high-speed read-only memory.
A further object of the present invention is to provide a data structure and a reproduction display device that can perform high-speed changeover of display images.